Android Open Source - GoCats Recycling Pager Adapter

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License

The source code is released under:

Apache License

Java Source Code

package com.jakewharton.salvage;
//w  ww.  j  av  a 2s . co  m
import android.support.v4.view.PagerAdapter;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import org.collegelabs.gocats.app.MainActivity;

/**
 * A {@link PagerAdapter} which behaves like an {@link android.widget.Adapter} with view types and
 * view recycling.
 */
public abstract class RecyclingPagerAdapter extends PagerAdapter {
    static final int IGNORE_ITEM_VIEW_TYPE = AdapterView.ITEM_VIEW_TYPE_IGNORE;

    private final RecycleBin recycleBin;

    public RecyclingPagerAdapter() {
        this(new RecycleBin());
    }

    RecyclingPagerAdapter(RecycleBin recycleBin) {
        this.recycleBin = recycleBin;
        recycleBin.setViewTypeCount(getViewTypeCount());
    }

    @Override public void notifyDataSetChanged() {
        recycleBin.scrapActiveViews();
        super.notifyDataSetChanged();
    }

    @Override public final Object instantiateItem(ViewGroup container, int position) {
        int viewType = getItemViewType(position);
        View view = null;
        if (viewType != IGNORE_ITEM_VIEW_TYPE) {
            view = recycleBin.getScrapView(position, viewType);
        }
        view = getView(position, view, container);
        container.addView(view);
        return view;
    }

    @Override public final void destroyItem(ViewGroup container, int position, Object object) {
        View view = (View) object;
        container.removeView(view);
        int viewType = getItemViewType(position);
        if (viewType != IGNORE_ITEM_VIEW_TYPE) {
            recycleBin.addScrapView(view, position, viewType);
        }
    }

    @Override public final boolean isViewFromObject(View view, Object object) {
        return view == object;
    }

    /**
     * <p>
     * Returns the number of types of Views that will be created by
     * {@link #getView}. Each type represents a set of views that can be
     * converted in {@link #getView}. If the adapter always returns the same
     * type of View for all items, this method should return 1.
     * </p>
     * <p>
     * This method will only be called when when the adapter is set on the
     * the {@link AdapterView}.
     * </p>
     *
     * @return The number of types of Views that will be created by this adapter
     */
    public int getViewTypeCount() {
        return 1;
    }

    /**
     * Get the type of View that will be created by {@link #getView} for the specified item.
     *
     * @param position The position of the item within the adapter's data set whose view type we
     *        want.
     * @return An integer representing the type of View. Two views should share the same type if one
     *         can be converted to the other in {@link #getView}. Note: Integers must be in the
     *         range 0 to {@link #getViewTypeCount} - 1. {@link #IGNORE_ITEM_VIEW_TYPE} can
     *         also be returned.
     * @see #IGNORE_ITEM_VIEW_TYPE
     */
    @SuppressWarnings("UnusedParameters") // Argument potentially used by subclasses.
    public int getItemViewType(int position) {
        return 0;
    }

    /**
     * Get a View that displays the data at the specified position in the data set. You can either
     * create a View manually or inflate it from an XML layout file. When the View is inflated, the
     * parent View (GridView, ListView...) will apply default layout parameters unless you use
     * {@link android.view.LayoutInflater#inflate(int, android.view.ViewGroup, boolean)}
     * to specify a root view and to prevent attachment to the root.
     *
     * @param position The position of the item within the adapter's data set of the item whose view
     *        we want.
     * @param convertView The old view to reuse, if possible. Note: You should check that this view
     *        is non-null and of an appropriate type before using. If it is not possible to convert
     *        this view to display the correct data, this method can create a new view.
     *        Heterogeneous lists can specify their number of view types, so that this View is
     *        always of the right type (see {@link #getViewTypeCount()} and
     *        {@link #getItemViewType(int)}).
     * @param parent The parent that this view will eventually be attached to
     * @return A View corresponding to the data at the specified position.
     */
    public abstract View getView(int position, View convertView, ViewGroup container);


}

Java Source Code List

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